1. Field of the Invention
This invention relates to polymeric dispersant additives for lubricants and hydrocarbon fuels. When of higher molecular weight, the additives are also useful as multifunctional viscosity-index improvers for lubricants. More particularly, this invention relates to hydrocarbon polymers such as tertiary hydrogen-containing or alpha olefin polymers and, in particularly, ethylene copolymers having a degree of crystallinity of less than about 25 weight percent as determined by X-ray or differential thermal analyses and comprising from about 2 to 98 parts by weight of ethylene and one or more C.sub.3 to C.sub.28 alpha olefins, usually propylene, which have been grafted by mechanical action as by intensive milling at an elevated temperature and in an inert atmosphere but in the presence of an amine compound to form an aminated polymer which is thereafter mechanically-oxidatively degraded as by intensive milling at an elevated temperature, usually in the absence of a solvent or fluxing medium and in the presence of air or oxygen-containing gas to form an aminated polymeric reaction product of reduced average molecular weight.
2. Description of the Prior Art
A variety of polymeric materials which incorporate nitrogen have been described in U.S. and foreign patents as dispersants for fuels and lubricants, and as viscosity index improvers for lubricants. For example:
U.S. Pat. No. 3,076,791 improves the pour point depressant activity of polymeric V.I. improvers by subjecting polymers and amines to shearing forces so as to effect degradation of the polymer whereby the pour point depressant activity was enhanced.
U.S. Pat. No. 3,404,091 grafts polar monomers, such as acrylonitrile onto hydroperoxidized copolymers of ethylene and propylene.
U.S. Pat. No. 3,404,092 reacts hydroxylated ethylenepropylene copolymers with isocyanates.
U.S. Pat. No. 3,687,849 grafts various unsaturated monomers onto a degraded, hydroperoxidized, interpolymer of ethylene and propylene.
U.S. Pat. No. 3,769,216 shows an atactic (i.e., non-crystalline) copolymer of ethylene and propylene containing from 45 to 65 mole percent of ethylene, mechanically degraded in the presence of oxygen, followed by reaction with a polyamine.
U.S. Pat. No. 3,785,980 discloses the reaction product of an amine with a hydroperoxidized atactic copolymer of ethylene and propylene containing from 45 to 65 mole percent of ethylene.
British Pat. No. 1,172,818 described the preparation of lube oil additives by the condensation of an amine with an oxidized, e.g., ozonized, polymer.